Jean Theory: How the FBI Has Solved Crimes Using Denim

The man who burst into Santa Barbara Savings and Loan demanding money on March 1, 1990, left few clues behind. Like most bank robbers, he wore a mask to obscure his facial features. But it wasn’t long before federal investigators believed they had found their man: James D’Ambrosio. When he went to trial, D’Ambrosio was found guilty, a verdict reached in part by evidence that appeared to implicate him.

One key exhibit? His blue jeans.

The FBI compared clothes including the denim jeans worn by the robber to clothes in D’Ambrosio’s possession that were found during a search of his residence. An expert witness for the agency testified that specific identifiers on the jeans—including wear marks, creases, and faded material—affirmed that they were the same pair. It was something like a denim fingerprint, and it assisted the jury in their decision.

D'Ambrosio would not be the only defendant to have their fate decided in part by their distinctive pants. And while some believe in forensic jeans science, others have cast doubt on whether it’s reliable enough to take defendants out of their Levi’s and put them into orange jumpsuits.

The Pants Detective

Law enforcement has always used the evidence left behind in a crime to identify suspects and prosecute cases. In 1910, Thomas Jennings became the first man to be convicted of a crime—murder—in the U.S. based on nascent fingerprint forensic science. He had left his prints on a railing during a burglary that led to his killing of the homeowner.

But fingerprints aren’t always left behind, which has necessitated novel techniques. In 1985, police discovered a dead body with a grasshopper nearby; the insect was missing a leg. To their surprise, a suspect’s pants had a grasshopper appendage stuck in the cuff. The body and leg were a match for each other.

Of course, it helps when there's visual evidence of a crime being committed. When security cameras became more commonplace at banks in the 1960s, they captured footage of robbers; some wore clothing that sported distinctive stains, though it wasn’t often that any definitive conclusions could be drawn: The picture quality was too poor to demonstrate all but the most egregious markings. (While camera resolution is still an issue today, it’s gotten markedly better.)

Indeed, James D’Ambrosio was not convicted solely on his choice of attire. In mounting its case, the prosecution offered that four tellers (of eight) were able to state with confidence that they could identify the robber’s voice. One teller testified she saw D’Ambrosio’s face before he pulled his mask down, though she had identified a different person in a photo lineup.

But it’s clear the jury lent credence to the idea his jeans were the same pair caught on camera. The technique also factored heavily when law enforcement was investigating a series of bombings and bank robberies in Spokane, Washington, in 1996. In the latter case, image examiner Richard Vorder Bruegge, Ph.D.—a onetime astronaut hopeful with the bureau’s Forensic Audio, Video and Image Analysis Unit—worked his theory that jeans grow increasingly worn and faded as they’re washed, particularly along the seams.

“Every piece of clothing that you own is going to undergo abuse during your lifetime,” Vorder Bruegge told The Chicago Tribune in 1999, the same year he published a scientific paper on the subject. “If you’re a kid, maybe you’re sliding down hills and getting a lot of scrapes on the jeans. Or maybe your jeans get washed and ironed. But you’re rubbing them back and forth, and the blue dye is abraded.” The erosion of that dye, he added, creates distinctive wear patterns. According to his paper,

“These characteristics may include folds, creases, and puckering which manifest themselves as high and low areas (‘ridges and valleys’) along and adjacent to the seams and hems. As the jeans are worn and washed over time, the visibility of these ridges and valleys is amplified through abrasion of the ridges, resulting in a loss of dark dye and marked tonal brightening. Given sufficient abrasion, even small ridges may exhibit sufficient contrast against the dye-rich background to be recorded on bank surveillance films, permitting a comparison with trousers recovered from suspects.”

When investigators working the Spokane case seized clothing from the home of suspect Charles Barbee, they found a pair of jeans that had over 24 seemingly unique fade and wear marks that matched the jeans of the suspect seen in a high-quality security camera photo. During the 1997 trial (in which Barbee was one of three men accused of the bombings and robberies), Vorder Bruegge testified the jeans were “100 percent” one and the same as the pair seen in the photo. A defense witness arguing that similar patterns could be found on multiple pairs of jeans was countered with FBI testimony that the jeans were all different. Barbee and the others were convicted.

But there were some who were already doubting the reliability of such evidence. Though Vorder Bruegge had declared the wear marks to be just as reliable as a kind of barcode, some critics have dubbed it little more than jean junk science.

“It Sounds Like Voodoo to Me”

In 2019, ProPublica reporter Ryan Gabrielson published a story examining the role of photographic evidence in prosecutions, a necessary component of introducing blue jean comparisons. This technique, Gabrielson wrote, was “rooted” in the Barbee case and is the cornerstone of the FBI’s Forensic Audio, Video and Image Analysis Unit. But how images are compared can harbor deep flaws.

The article points out that Vorder Bruegge testified in a 2003 case that a plaid shirt found in a suspect’s possession was identical to the one worn by the suspect in a series of bank robberies in Florida. Lines in the shirt pattern along the seams could be matched, he said, and the chances of two shirts being so alike were as little as 1 in 650 billion. But without an extensive database of such shirts, it can be hard for some to accept such a definitive claim. (The jury, however, did: The suspect was found guilty.)

Alicia Carriquiry, a statistics expert and Iowa State University professor, has argued that sewing machines could easily replicate stitch and seam irregularities across many pairs of jeans. And in 1999, Jack King, a spokesperson for the National Association of Criminal Defense Lawyers, observed that the unreliable quality of surveillance footage can be prohibitive to accuracy.

“Even with digitally enhanced photography, I have severe doubts about this technique, and will continue to have severe doubts until it's proven conclusively,” King said. “It sounds like voodoo to me.”

In 2020, a study published in the Proceedings of the National Academy of Sciences cautioned against absolute conclusions in wear patterns on jeans. Computer scientist and study co-author Dr. Hany Farid told The New York Times he was actually motivated to examine the technique based on the ProPublica article. Farid and a colleague purchased 100 pairs of jeans and solicited several more online, photographing the vertical seams of each pair under a number of conditions. Computer software analyzed the seam differences, or ridges and valleys, to see if they were consistent among different photos.

Dr. Farid discovered that regardless of jeans having unique wear patterns, it was difficult for the same pattern to be reliably photographed. One pattern may appear differently in one image than in another. This is likely because cloth can bend, fold, and contort itself so easily that it takes on a chameleonic appearance. Jeans worn by a person in motion will appear visually different than if those exact same jeans were photographed while splayed out on a table; poor image capture from surveillance only compounds the problem.

He put a positive match rate for his experiment at 20 percent. This lack of consistency, Dr. Farid argued, makes the usefulness of forensic clothing comparison limited.

Despite the voiced concern, both the FBI and the justice system appear to have confidence in the method; such image examination continues to be an element of criminal cases. As for alleged bank robber D’Ambrosio: After being found guilty, he filed an appeal that was brought before the U.S. Court of Appeals for the Ninth Circuit and heard in August 1993. The appeals court affirmed the guilty verdict.

Are worn jeans enough to nail future suspects? That remains to be seen. But should you find yourself entertaining the idea of committing a crime, you might be better off in sweatpants.

Read More About Jeans: